One benefit to the IAD Marriott is that it allows you to use the toll-free lanes of the Dulles toll road so that you can get into D.C. and back for free. It is an old place, but I kind of like it and the lounge is pretty good.
I am at the Fair Oaks Marriott now, I like this one too. I have stayed at the Marriott Suites and did not care much for it. I like the FS Marriott's on the weekends that provide breakfast coupons, since I only really get to eat breakfast on the weekend. The rest of the week I have to hit the toll road or I-66 (depends on where I am staying) before breakfast starts at most hotels. Why is it the only start serving at 0630, sometimes as late as 0700.